Machine for polishing or grinding cam tracks and like sinuous surfaces



July 12, 1932. DOUGLAS MACHINE FOR POLISHING OR GRINDING CAM TRACKS AND LIKE SINUOUS SURFACES Filed April 1. 1951 2 Sheets-Sheet 1 PER ZQ'TDRNEY INVENTU I JuHN BEURBEDUUIQLiS July 12, 1932. J, G, DOUGLAS 1,867,213

MACHINE FOR POLISHING OR GRINDING CAM TRACKS AND LIKE SINUOUS SURFACES Filed April 1, 1951 2 Sheets-Sheet 2 LhJHN PER INVE TBR EEIREE uusqs TTU NEQ Patented July 12, 1932 UNITED STATES JOHN GEORGE DOUGLAS, OF LEAGRAVE, LU'ION, ENGLAND PATENT OFFICE MACHINE roe POLISHING on GRINDING cAivi TRACKS Ann LIKE sinuous scanner-is Application filed April 1, 1931, Serial No. 526,890, and in Great Britain May 6, 1930.

This invention relates to improvements in machines for polishing or grinding cam tracks and like sinuous helical surfaces. The invention is particularly useful where it ,5 is required to polish or grindthe tracks or grooves of worms or cams in which the pitch is not constant and/or in which the groove is terminated at one or both ends by solid metal and/or which have been generated to engage with a conical peg or a roller adapted to move in a non-rectilinear path, for instance as adopted in the production ofv automobile and the like steering gears. The practice adopted heretofore in finishing or polishing these worm spindles or cam'groovesshafts is to execute the operation by hand by reason of the difliculty with machines of ensuring that the polishing mop will during its rotation follow accurately the predetermined nonconstant helical path due to the varying pitch, depth of groove and flank angles. My present invention provides a machine in which regularity and accuracy in polishing or grinding is obtained irrespective of whether the cam like or sinuous surface to be treated is of uniform pitch throughout or of varying pitch, the object of my invention being to provide improved and faster means with such a machine which will obviate the necessity of hand polishing and will avoid adjustments by the operator during the polishing or grinding operation. 7

In a polishing or grinding machine according' to my invention the pitch of the work determines the translating movement necessary for the polishing or grinding member to act along the faces of theworkto be polished or ground.

A holder is provided for the work which is translatably movably supported in such manner that the pitch of the cam or like. surfaces of the work effects a movement of translation of the holder automatically synchronously with the change in surface of the work being polished or ground;

In the preferred form of my invention the work is readily detachably held in a holder suspended 'pivotally from a support so that the work presses downwards and laterally against the polishing or. grinding tool bob or mop, the said holder being free to move under the cam act-ion influence of the work against the tool bob or mop.

' In order that my invention may be clearly understood and readily carried into effect, I have appended hereto two sheets of drawlngs illustrating embodiments thereof and wherein, Fig.1 is-a perspective view showing the machine in use. 1

Fig. 2 is a detail broken perspective view showing an alternative method of carrying the work holder.

Figs. 3 and 4 are detail views showing alternative forms of mops; j Fig. 5 is a part sectional side elevation.'- Figs. 6 and *7 are longitudinal sections 7 through the mandrils for holding the work. Referring to the'drawings I can employ a. mop spindle I of usual type, the mop '2 of which can be charged with abrasive emery powder or the like on its face, the spindle preferably being on a horizontal, axis. in a plane between the ends of anupright pillar 3 adjustab-ly supported by a base 4 which can be, secured fast to the floor. Supported at its centre across the upper end of the said pillar is a wide U shaped bracket 5 which iscarried by a collar 6 which can be adjusted up and down and angularly around the pillar 3 to a desired height and angular position. This arrangement allows the height of the said bracket to be set so as to bring the centre line of the work to be polishedin the plane containing the axis of the said mop spindle. The U shaped bracket 5 canswivel abouta horizontal axis in all its positions sothat the said bracket 5 can be swung round the pillar 3 and also assume any angle relative to the axis of the mop carrying spindle asmay be necessary. 0

For this purpose the centreofthe bracket 5 can pivot on aspin 7 fixed to the collar 6, a

pair of studs'8 threaded into the collar and engaged in arcuate slots 9 in the bracket. 5 concentric with the pin? providing a means of securingthe said'bracket in-selected angular relationship to the pillar 8. g

Y Thefree ends of the side arms of the said U shaped bracket 5 are formed'withbosses lO V bridged by a, guide shaft 11, and this guide shaft which is arranged parallel to the axis of guide shaft 11 and they respectively support @co-axial man-dri-ls 14 and 14a free to rotate in the arms 12 and adapted to support be-,

tween them the work 15.

One end of one of the mandrils is capable of being withdrawn by a milled head 16 against a coiledcompression spring 23 inside a housing 18 on the appropriate arm-12so that the work can be inserted between the mandr-ils. The other mandril 14a is adapted itobe continually rotated at any suitable speed preferably-by a worm '24 and worm wheel accommodated in a housing 19 on the other arm-l2 of the said frame and driven by a flexible shaft 20 from the overhead works of the shop or by anelectric motor, orany other suitable source of power. A driving'shaft 21 passesthrough this mandril and rotates with the mandr'il but can slide axially on feathers 22 in the mandril. Theinne'r end of this driving shaft '21 of the, mandril is for-med to engage with the serrations" or other suitably shaped parts formed in an "end face or in the bore er the cam or other work '15 being polished. An exchangeable distance piece 26 is'thre'aded into thein-ner end of the shaft'21 to enable different axial dimensions ofwork 'tobe comp'en'sated for. The inner end of the other mandr-illiis also suitably formed to receive one :of the *ends 'of the work.

A substantially horizontal arm '27 "is piv eoted atone end to alug 28 on the said. U

shaped bracket and this arm is formed near its free end with a slot 29 which can beenga'ged over a transverse rod 30 onithe said depending work earrying frame 12 for holding the Work clear of the polishing mop 2 to enable 'the spring loaded 'mandril 14 to :be

retracted to release the work.

Whenpolishmgza'wormofa steering pillar of a motor road vehicle asshown in Fig. for

for like work, the pillar 3 is adjusted tothe required-extent relative to the base 4 to set the work'wi'th relationito the mop spindle soeth'at when one fa'ce o f lt'he mop 2 is Lin contact with "one'side' of theflanjk:ofthegroovein the cam -or worm thesaid dependingframe '15'does not lie ver'tijcal lybut forms:an anglev with the said upright "pillar 3'sovthat according to such angle theworm is pressed by :gravity against the appropriate faceofithe mop and-with such degree of force-as may required This 7 e pressureinaybe enhanced bya tension spring "l'connecte d'to the depending frame 12 and to the-centre of the ll shaped ibracketfi. The

said U shaped bracket is swung round a vertical aXis constituted by the said pillar so that the said face of the mop 2 is in contact radially right'across the selected side of the face of the groove in the cam. The frame 12 and bracket 5 are also set at such angle as may be necessary to obtain an axially directed pressure between the said face of the mop and the appropriate side of the flank of the The polishing then proceeds without the workman having to touch the said frame or handles, the revolving worm or like work with its helical groove causing the said frame to slide along :the said guide shaft at such varying speed as the variable pitch of cam or worm itself may require.

As the pressure between the mop face and I the sideiof cam track is constant at all points, and rotation of the cam or otherlike work is constant, polishing or grindingof oneside of the c'am trac'k is perfectlyregu-lar and the formation, helix angles, side angles ofitrack etc, are. exactly the same after polishing vor grinding as before such operation.

When the work has traversed across the mop from one end to the other, the workman swings the said frame ,5 up and away from the mop so that the slot 29 of the arm :27 drops over the said I transverse rod 30 of the frame, and holds the :frame stationary ion clear ofthe mopJ The 'wiorkis then reversed s end for end, and the other side of cam track is polished or ground in the same way.

Alternatively the mop 2 can :be formed with two inclined working faces :and a working periphery asshown .in Fig. 4 so that both sides of groove are polished or ground at the same time. Inthis case bothsides of the mop are coatedlwith a suitable abrasive.

An alternative form of bracketland depending frame in which the frame does not slide along a guide shaft, but swings can be adopted. For this purpose the sliding movement of "the said frame can be replaced by a parallel link like motion 'as shown .in Fig. 2 by connecting the ends of a rod 32 passing through the upper corners of the 7 said frame 12 by a pair :of depending parallel links 33 to the said "bracket 5. V

The pillar 3 can beadjusted'along a verticalpl'ane in a slotf34 in theb'ase 'by means of a'handwheel 35 fixed onashaftfifith-reade'dinto a collar on the lower end 30? the pillar The pillar can turnedxaxi'ally in said collar and clamped by .atnut 37 acces sible by a tommy bar through an opening 38 in the base 4.

What I claim is 1. In a polishing or grinding machine a 51 mop or tool holder a pair of axially aligned spaced work holders between which the work is adapted to be held, means with one of said holders for rotating the work axially, a substantially horizontal guide above said holders, the said holders being suspended from beneath said guide by means freely slidable along said guide whereby the work by its engagement with the tool or mop constitutes the sole means of imparting a movement of translation to the work holders.

2. A polishing or grinding machine comprising a bracket, a rod supported substantially horizontally across said bracket, a work holder rotatable at one end about said rod and free at its other end, a pair of spaced work receiving devices at the free ends of said holder, means with one of said devices for rotating the work, a tool or mop for engaging the work located beneath said rod, the said holder being freely slidable along said rod, a pillar, a member slidably adjust able along said pillar and means angularly adjustably connecting said bracket to said pillar. I

3. A polishing or grinding machine comprising a bracket, a rod supported substantially horizontally across said bracket, a work holder rotatable at one end about said rod and free at its other end, a pair of spaced work receiving devices at the free ends of said holder, means with one of said devices for rotating the work, a tool or mop for engaging the work located beneath said rod, and links pivoting said rod to said bracket so that the said work holder is free to move in a direction substantially parallel with the axis of the work, a pillar, a member slidably adjustable along said pillar, and means angularly adjustably connecting said bracket to said pillar.

4:. A polishing or grinding machine comprising a bracket, a rod supported substantially horizontally across said bracket, a work holder rotatable at one end about said rod and free at its other end, a pair of spaced work receiving devices at the free ends of said holder, means with one oi said devices for rotating the work, a tool or mop for enaging the work located beneath said rod, the said holder being freely slidable along said rod, a pillar, a member slidably adjustable along said pillar and means angularly adjustably connecting said'bracket to said pillar, a base for said pillar and means for adjusting the pillar relative to said base.

5. A polishing or grinding machine comwork receiving devices at the free ends of said holder, means with one of said devices for rotating the work, a tool or mop for engaging the work located beneath said rod, and links pivoting said rod to said bracket so that the said Work holder is free to move in a direction substantially parallel with the axis of the work, a pillar, a member slidably adjustable along said pillar, and means angularly adjustably connecting said bracket to said pillar, a base for said pillar and means for adjusting the pillar relative to said. base.

In witness hereof I have signed this specification.

JOHN GEORGE DOUGLAS.

prising a bracket, a rod supported substantially horizontally across said bracket, a work holder rotatable at one end about said rod, and free at its other end, a pair of spaced 

